It is often necessary to dry enclosures such as the interior of buildings, for example after flooding or to dry out new construction. It is known for example that raising the temperature of air reduces the relative humidity of air. Systems are know which draw outside air through a heater to reduce the relative humidity thereof, and direct the dried air stream into an enclosure at one end thereof and exhausting the air stream at the opposite end thereof. As the air stream moves through the enclosure it absorbs moisture that is carried out with the exhausted air stream. The operation of such a system is described for example in U.S. Pat. No. 7,243,442 to Myerholtz et al.
Another popular type of drying system uses a desiccant wheel, such as the mobile desiccant dehumidifier as described in U.S. Pat. No. 6,652,628 to Hess. A wheel is filled with a desiccant such as silica gel or the like, and turns slowly. Moist process air is passed through the thickness of a first process portion of the wheel and as the process air passes through the wheel moisture is drawn out of the process air and into the desiccant, and a dry air stream is discharged into the enclosure. A warmed reactivating air stream, with consequently reduced relative humidity as described above, is then passed through a second reactivating portion of the wheel and draws moisture out of the desiccant, and a wet exhaust air stream is then exhausted outside. Thus the desiccant in the slow turning desiccant wheel absorbs moisture from the process air stream flowing into the enclosure and then transfers that moisture to the reactivating air stream flowing to the outside.